Utilities department outlines stormwater post-construction BMP compliance plan under MS4 permit

The Topeka City Utilities Department presented a post-construction stormwater compliance program to the Infrastructure Committee on April 15, laying out work to identify and inspect private and public best management practices (BMPs) required under the municipal separate storm sewer system (MS4) permit.

Staff said the program responds to an EPA audit (2018 audit with final report in 2019) and a resulting consent agreement that requires improved compliance and inspection of post-construction BMPs. The Clean Water Act requires a National Pollutant Discharge Elimination System (NPDES) permit; Topeka operates under a phase I MS4 permit and must implement six minimum controls including post-construction stormwater management.

What staff described

City staff said they have cataloged roughly 190 BMPs (private and city-owned) and developed a database that will support inspections and enforcement. The program includes an owner-notification letter and an 11-question survey to establish a baseline of owner knowledge and the number and condition of BMPs on each property. The city plans QR-coded access to an online survey and resources once the new stormwater web pages are live.

Staff described enforcement as a last resort and emphasized education and technical assistance. They said most older BMPs were designed 20-plus years ago and can look out of place in neighborhoods; newer designs aim for better aesthetics and lower maintenance complaint. City-owned BMPs will also be inspected and maintained by the city.

Key thresholds and timelines

Staff said post-construction inspection and reporting requirements have applied since 2021 for qualifying projects. Generally, developments equal to or greater than one acre trigger post-construction requirements. The department said it planned to continue sending letters and pushing for survey responses in 2025 and to report progress to EPA in the city's annual stormwater report due in February 2026. The goal is to demonstrate sustained compliance and lift the consent agreement.

Questions from council members

Council members asked how the city will help owners who cannot perform maintenance (for example, elderly or out-of-area owners); staff said education, technical assistance and targeted outreach will be provided, and that enforcement is available if voluntary compliance fails. Council members also asked about a searchable database of BMPs and staff said the database is under development and will be used to identify owners and prioritize outreach.

Why it matters

Post-construction BMPs are intended to keep runoff near its source, reduce downstream impacts and improve water quality. The city's MS4 permit, federal audit findings and the consent agreement make progress on BMP inspection and compliance a regulatory priority.

Ending

Staff asked for committee acknowledgment of the outreach plan and said they will return with updates on survey response rates, inspection results and any enforcement actions.